Practice Corner MCQ

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(c) : Biodiversity is the term popularised by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation.

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(b) : Genetic diversity is the diversity in the numbers and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species. The genetic variation in Rauwolfia vomitoria growing in different Himalayan ranges indicates genetic diversity. This diversity is in terms of potency and concentration of the active chemical reserpine, that plant produces.

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(c): India has 1,000 varieties of mango. This is due to the genetic diversity i.e., a single species show high diversity at the genetic level over its distributional range.

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(a) : Species diversity is the variety in the number and richness of the species of a region. Western ghats have greater amphibian species diversity as compared to Eastern ghats. The number of the species per unit area is called species richness. Number of individuals of different species represent species evenness or species equitability.

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(b) : Ecological diversity is the diversity at ecosystem level. India with its deserts, rainforests, mangroves, coral reefs, wetlands, estuaries and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

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(a) : Ecological diversity is of three types:
(i) Alpha diversity (Within community diversity)
(ii) Beta diversity (Between community diversity)
(iii) Gamma biodiversity is diversity of habitats/ecosystems over a total landscape or geographical area.

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(a) : Ecological diversity is of three types:
(i) Alpha diversity (Within community diversity)
(ii) Beta diversity (Between community diversity)
(iii) Gamma biodiversity is diversity of habitats/ecosystems over a total landscape or geographical area.

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(a) : A more conservative and scientifically sound estimate about the total number of species present on earth, was made by Robert May.

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(c) : Robert May estimated that about 7 million species are present on earth.

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(b) : Animals constitute more than \(70 \%\) of all the species recorded whereas plants constitute around \(22 \%\) of total number of species.

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(a)

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(c) : There are 72,000 species of fungi – \(A\) and \(2,70,000\) species of higher plants angiosperms – \(B\) in the world.

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(d)

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(b) : India is one of the twelve megadiversity regions of the world with \(8.1 \%\) of genetic resources of the world. Wildlife Institute of India has divided the country into 10 biogeographical regions – 1. Trans-Himalayas, 2. Himalayas, 3. Desert, 4. Semi-arid, 5. Western Ghats, 6. Deccan Peninsula, 7. Gangetic Plain, 8. North East, 9. Coasts, 10. Islands.

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(c): Colombia located near the equator has nearly 1400 species birds, New York has 105 species, Greenland has only 56 species. India has around 1200 species.

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(a)

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(d) : If we accept May’s global estimates only \(22 \%\) of the total species have been recorded so far.
If May’s proposal for discovery of new species is accepted then there are probably more than \(1,00,000\) plant species and more than \(3,00,000\) animal species yet to discovered and described.

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(a) : Biodiversity changes with the change in altitude. It increases as one moves from higher to lower altitudes. Decrease in temperature and greater seasonal variability are the two major factors responsible for lower diversity at higher altitudes.

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(a) : The biodiversity shows a latitudinal and altitudinal gradients. The species diversity decreases as we move away from the equator towards the poles with very few exceptions, tropics harbour more species than temperate or polar areas.

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(c) : Biodiversity is affected by latitudinal gradients.

Tropics \(\left(23.5^{\circ} \mathrm{N}\right.\) to \(\left.23.5^{\circ} \mathrm{S}\right)\) have more species than temperature or polar regions. For example, Colombia located near the equator has nearly 1400 species of birds, while New York \(\left(41^{\circ} \mathrm{N}\right)\) has 105 species and Greenland \(\left(71^{\circ} \mathrm{N}\right)\) has only 56 species.

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(d) : In tropics where species continued to flourish and evolve undisturbed there are no unfavourable seasons in tropics for millions of years. Continued favourable environment has helped tropical organisms to gain more niche speciallisation and increased diversity. More solar energy is available in tropics. This promotes higher productivity and increased biodiversity.

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(a)

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(c) : The slope of the line is much steeper if we analyse the species- area relationships among very large areas like the entire continents. For example, for fruit-eating (frugivorous) birds and mammals in the tropical forests of different countries, the slope is found to be 1.15 .

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(b) : Ecologists believe that the communities with more species tend to be more stable than those with less species. This was confirmed by David Tilman.

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(d) : A stable community is self-perpetuating and final biotic community that is in perfect harmony with the physical environment. It does not show much of changes and is usually resilient to natural or man made disturbances. It is also resistant to invasion by alien species.

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(d) : Keystone species are those species which have significant and disproportionately large influence on the community structure and characteristics. It has often considerably low abundance and biomass as compared to dominant species. Removal of such species causes serious disruption in structure and function of community.

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(a)

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(a) : IUCN is International Union of Conservation of Nature and Natural Resources, which is now called World Conservation Union (WCU). It has its headquarters at Morges, Switzerland. It maintains a Red Data Book or Red List which is a catalogue of taxa facing risk of extinction.

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(a) : Red Data book is a catalogue of taxa facing risk of extinction. It is maintained by IUCN.

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(d): The IUCN Red List, 2004 documents the extinction of 784 species including 338 vertebrates, 359 invertebrates and 87 plant in the last 500 years.

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(c)

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(d) : Bali, Javan and Caspian are the three subspecies of tiger.

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(a) : According to updated IUCN red list, Antilope cervicapra (Blackbuck, Indian gazelle) is a least concern species.

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(c) : Passenger pigeon and Dodo are extinct birds. Zebu is name of a cattle which is not endangered. The Great Indian Bustard is critically endangered as per IUCN.

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(d)

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(c) : Extinction due to human activities is called anthropogenic extinctions.

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(d) : There are four major causes of biodiversity losses which are collectively called as-the evil quartet. These are habitat loss and fragmentation, over-exploitation, alien species invasion and coextinctions.

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(b) : Tropical rainforests are disappearing fastly from India due to deforestation, habitat loss and fragmentation. These forests are of extreme value since they contain the maximum biodiversity.

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(b) : Excessive exploitation of a species, whether a plant or animal reduces size of its population such that it becomes vulnerable to extinction. Dodo, passenger pigeon and Steller’s sea cow have become extinct in the last 500 years due to over-exploitation by humans.

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(b) : Non-native or exotic species are often introduced inadvertently for their economic and other uses. They often become invasive and drive away the local species. These species are considered to be second major cause of extinction of species. Such invasive exotic species have proved harmful to both aquatic and terrestrial ecosystems e.g., Lantana, Eichhornia and African catfish.

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(c) : Nile Perch (a predator fish) was introduced in lake Victoria of East Africa. It killed and eliminated ecologically unique assemblage of over 200 native species of small cichlid fish.

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(d) : Lantana, Eichhornia and Parthenium are all exotic species, which had been introduced in India. Lantana camara has replaced many species in forests of Uttar Pradesh and Madhya Pradesh. Eichhornia (Water hyacinth) has clogged water bodies including wetlands resulting in death of several aquatic plants and animals. Parthenium has pushed out several herbs and shrubs from open places in the plains.

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(a) : Clarias gariepinus, the African catfish has been illegally introduced for aquaculture in India. It is threatening native catfishes (Clarias gariepincy) of Indian rivers.

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(c) : In the absence of their natural predators, exotic species flourish better and pose a threat to indigenous species.

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(b) : The world is facing accelerated rates of species extinctions, largely due to human interference. There are four major causes collectively called as -the evil quartet, it includes (i) Habitat loss and fragmentation; (ii) Over exploitation; (iii) Alien species invasions and (iv) Co-extinctions.

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(d) : The world is facing accelerated rates of species extinctions, largely due to human interference. There are four major causes collectively called as -the evil quartet, it includes (i) Habitat loss and fragmentation; (ii) Over exploitation; (iii) Alien species invasions and (iv) Co-extinctions.

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(c) : Humans derive countless direct economic benefits from nature that come under narrow utilitarian category. These benefits include food, fibre, construction material, etc. More than 25 percent of the drugs currently sold in the market world wide are derived from plants and 25,000 species of plants contribute to the traditional medicines used by native people around the world.

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(b) : Bioprospecting is the exploration of molecular, genetic and species level-diversity for gaining the products of economic importance. It comes under narrowly utilitarian category.

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(c) : About 20% of the world oxygen is produced in the amazon rainforests. They are described as the ‘lungs of the planet’ because they provide the essential world environmental service of continuously recycling \(\mathrm{CO}_2\) into \(\mathrm{O}_2\).

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(c) : Ecosystem services like photosynthesis; pollinators layer of bees, birds and bats; aesthetic pleasure of walking through thick woods and watching spring flowers in full bloom are some arguments that come under broadly utilitarian category.